[test] Remove FLAG_always_opt special case in NotifyDeoptimized

Always unlink optimized code on deopt, even when FLAG_always_opt is present, because assumptions that the code made could have become invalid.
BUG=v8:4375
LOG=n
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/1284103006

Cr-Commit-Position: refs/heads/master@{#30196}

src/runtime/runtime-compiler.cc

@@ -132,9 +132,7 @@ RUNTIME_FUNCTION(Runtime_NotifyDeoptimized) {
   RUNTIME_ASSERT(frame->function()->IsJSFunction());
   DCHECK(frame->function() == *function);
 
-  // Avoid doing too much work when running with --always-opt and keep
-  // the optimized code around.
-  if (FLAG_always_opt || type == Deoptimizer::LAZY) {
+  if (type == Deoptimizer::LAZY) {
     return isolate->heap()->undefined_value();
   }